The present invention relates to a cutting insert for a cutting or breaking tool, which can be mounted in a tool holder that can be rotated about a longitudinal axis, and especially to a lathe chisel as well as to such a cutting or breaking tool itself
Such tools are rotatably mounted in tool holders, which are usually fastened to a surface of a rotating roller. In the case of tools known in practice, heads of tool bodies and intermediate regions of cutting inserts are conical and constructed with a round cross section. A different hard alloy insert, described in the WO 94/13932, has a ribbed intermediate region, as a result of which an improved spatial behavior is to be attained, since the regions between the ribs serve to carry away material that has been cut off or broken off. However, because the material to be processed generally contains tar, the spaces between the ribs clog up quickly, so that the improved spatial behavior exists for only a short time.
It is therefore an object of the present invention to provide a generic cutting insert as well as a generic cutting or breaking tool, which has improved and durable spatial as well as cutting and breaking properties.
Pursuant to the present invention, this objective is accomplished by a cutting insert with a substantially conical tip, a transition region connected to the substantially conical tip having spatial areas distributed over a periphery of the transition region and adjoining one another to form cutting edges, and a foot connected to the transition region for connecting with the cutting or breaking tool.
The present invention further provides a cutting and breaking tool, especially a lathe chisel, for mounting in a tool holder so that it can be rotated about a longitudinal axis, with a head and a tool body having a shaft and a cutting insert as described above.
Due to the spatial areas, which are disposed distributed over the periphery of the transition region of the cutting insert and which, in comparison with a cutting insert of circular cross section, are disposed in secant fashion, free regions are formed between the edges of these spatial areas adjoining one another. As the tool is rotated, waste material is ejected from these free regions and transported out of a working region without sticking or clogging. Since the edges are constructed by spatial areas as cutting edges, they have an additional peeling action during rotation of the tool. This peeling action reinforces the cutting action of a tip of the cutting insert, so that a depth of penetration and a service life of the tool as a whole are improved and, as a result, the lathe chisel remains sharp longer.
Further advantages and details arise out of further features and embodiments of the present invention, which are explained in the following and shown in the drawings.